1. Field of the Invention
The present invention pertains to a sampling and holding circuit signal having low sampling residual component, especially for the dual sampling of correlated signals given by charge-transfer devices, these signals being video signals among others.
2. Description of the Prior Art
Sampling and holding circuits are made in the prior art by means of a cell that memorizes samples of signals given by a current switch and a capacitor. In these devices of the prior art, the current switch often comprises a field effect transistor connected by a source or drain electrode to the capacitor, the other electrode (either drain or source respectively) receiving the signal to be sampled. The "on" or "off" state of the current switch thus formed is controlled by sampling pulses applied to the gate electrode of the field effect transistor. At each sampling pulse, a current flows in the field effect transistor which charges the capacitor throughout the time when the control pulse is applied.
However, the inter-electrode capacitances of field effect transistors are the cause of residual, interference voltages at the frequency of the control signals which are superimposed on the sampled signal at the output of the sampling circuit.